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Saturday, July 20, 2019

Here are key references for understanding the cause and
evidence for global warming and climate change. Also included are references for some of the consequences with a focus on
Alaska.Some of the references link to
primary data (such as atmospheric data at Scripps); some assembly may be
required.

NOAA Greenhouse Gas Index.Page includes formulas for predictive calculation of radiative forcing
as function of concentration, and a table for historical annual radiative
forcing for major greenhouse gases.

Wednesday, June 27, 2018

Greenland’s ice cap is melting. Antarctica’s ice cap is melting. Arctic sea ice is melting. Continental
glaciers are melting.Arctic permafrost
is melting.The melting is happening at
a rate that is readily visible to people who live near natural ice.From decade to decade and year-to-year, glaciers are visibly retreating, and can be directly verified by the most casual
observer.

Melting ice is the second most important heat sink on the
planet, after the ocean (albeit a distant second).Melting ice accounts for about 3% of
anthropogenic heat retained in the atmosphere.Melting ice is the second most significant proof that human-caused
climate change is happening.Melting ice
may be the most significant consequence of climate change in terms of costs
and damage to humanity.

The data is unambiguous and irrefutable.The volumes of melted ice have been measured
by a variety of methods, including high accuracy satellite measurements.The heat required to warm and melt this
volume of ice can be calculated and compared to the heat trapped in the
atmosphere by greenhouse gases, and the rising heat content of the oceans.The volume of meltwater entering the ocean
can also be compared to measurements of rising sea level. The rate of sea level rise is already 3 times the rate of the past 7500 years, and accelerating. The observed volumes of melting ice and the measurement of rising sea level provide unambiguous proof that climate change
is real.

Greenland

Ice on Greenland is melting.

Greenland covers an area one-fifth the size of Australia.Almost all of Greenland is covered by ice,
ranging between 1 and 2 miles of ice thick.The Greenland Ice sheet contains more than 2.8 million cubic kilometers
of ice. That is enough to make sea level rise by 20 feet if it all melted.

NASA’s GRACE (Gravity Recovery and Climate Experiment) satellites
have monitored the mass of the Greenland ice cap since 2002.Gravity observations were supplemented by
altimetry and radar data from overflights and satellites.Other satellite observations include NASA’s
early ICESat, and the ESA’s currently operating CryoSat2.

There is a strong seasonal signal in the history of ice loss
from Greenland, with a slight build in ice mass during the Northern Hemisphere
winter, and a stronger decline in the summer. From 2002 to 2016, Greenland lost about 3900
gigatonnes of ice due to melting. Each gigatonne is a little more than one cubic kilometer of ice by volume, and produces one cubic kilometer of fresh water when it melts. Altimetry data show that most of the melting was concentrated near the
coast, particularly on the western side.Six feet to fourteen feet of ice has melted around the edges of the entire
island.

The GRACE satellite, designed for only a five-year life,
actually worked for nearly fifteen years.The last data was recorded in June 2017.The replacement mission, GRACE Follow-On, is scheduled to be launched in
five days, on May 19th, 2018.

NASA’s IceBridge is an airborne project using laser
altimetry and ice-penetrating radar data to measure the elevation, snow cover,
and total thickness of Greenland and Antarctic ice.IceBridge will provide data to connect and
calibrate data from the new GRACE satellites.IceBridge was originally designed to replace data from the ICESat satellite, which failed after seven years of service.ICESat-2 is planned to be launched in
September, 2018, to replace ICESat.

Antarctica

Ice on Antarctica is melting.

Antarctica is about seventeen times larger than Greenland,
and nearly twice as large as Australia.Ice covers 98% of the continent, to an average thickness of over a
mile.Antarctica holds about ten times
the volume of ice as Greenland.If all
of the ice on Antarctica melted (which would require centuries to occur), it
would raise sea level by about 200’, placing most of the world’s major cities and human habitation under water.

The GRACE data for Antarctica is noisier than the data for
Greenland and shows a weaker seasonal cycle.It seems likely that the melting season over Antarctica is not (yet) as
profound as over Greenland.

As with Greenland, the Antarctic ice sheet has been
monitored by NASA’s Grace and ICESat satellites, and the IceBridge aerial
observation program.Earlier
observations were integrated by the European Space Agency’s IMBIE (ice sheet
mass balance comparison exercise) to provide the ice balance record from 1992
to 2010.The chart showing both IMBIE
data and GRACE data is shown below.From
1994 through 2017, at least 2450 gigatonnes of ice on Antarctica melted.

I should note that gravity methods will not detect ice loss
on the portions of the ice sheet that are floating (and more susceptible to ice
loss).Ice floating on water will have
the same net density as ice-free water.So,
altimetry methods must be combined with gravity methods for a full
determination of ice loss on Antarctica.The East Antarctic (Filchner-Ronne) and West Antarctic (Ross) ice
shelves are approximately 900,000 square kilometers in area.Dozens of smaller ice shelves also exist.The actual loss of ice from Antarctica may be
greater than 2450 gigatonnes, because losses from these floating ice shelves
are not detected by gravity.

While melting of floating ice shelves is difficult to
observe, it is also true that the melting of floating ice will not cause sea
level to rise, at least as a first-order consequence.The same buoyancy of ice shelves that makes sea-ice loss invisible to gravity detection means that sea level does not change
when a volume of ice is converted to water.Melting ice shelves matter to the earth’s heat budget, but not
(directly) to sea level.

The rate of future ice loss in Antarctica depends on feedback
mechanisms.The principle feedback
mechanism is the restraining force that ice shelves exert on flowing
glaciers.Ice shelves impede the flow of
ice from the continent and into the ocean; when those shelves melt, the rate of
ice loss will accelerate.The timing and
amount of acceleration are unpredictable, so the best estimates of future sea
level rise are uncertain on the high end.We are fairly certain about the minimum expected sea level rise, but the
maximum possible sea level rise is very uncertain.

Antarctic Sea Ice

For many years, Antarctic sea ice was not subject to the
declines seen in Arctic sea ice (seen in the next section).This was often referenced in commentaries on
climate-change deniers’ web sites.In
recent years, Antarctic sea ice has
declined, but it is likely to continue to show an irregular response to climate
change.The reason is simple.Antarctic sea ice is regularly replenished by
calving from Antarctic glaciers and ice shelves.Anyone with tour-boat experience in Alaska
knows that sea ice actually increases following calving events.So, with a huge reservoir of ice in the
Antarctic ice cap, Antarctic sea ice is likely to fluctuate, but not disappear,
as the mother-lode of ice continues to flow and break apart, feeding the sea
ice around the continent.

Arctic Sea
Ice

Arctic Sea Ice is melting.

In contrast to Antarctica, the Arctic has no mother-lode of
ice feeding the polar sea ice.The sea
ice freezes and melts in a seasonal cycle.For the past forty years, each cycle has ended with less ice, on
average, than the previous cycle.The
loss of ice has accelerated over that period.There was about 250,000 square miles less sea ice in the 1990s than
during the 1980s.From the 1990s to the
2000s, the decadal average showed a loss of about 500,000 square miles of sea
ice.The annual data from the current
decade suggests an even greater rate of loss.

Area is not the only measure of sea ice.Some sea ice persists through multiple
seasons, gaining thickness from season to season.However, against the background rate of
general melting, less and less ice persists from season to season, and the
overall thickness of Arctic sea ice is also declining.Between 1984 and 2016, 94% of the sea ice more
than four years old had disappeared.

Image by M Tschudi and S. Stewart of the
University of Colorado, and W. Meier and J. Stroeve of NSIDC.

Some researchers have attributed 30 percent to 50 percent of
the loss of Arctic sea ice to natural variability, and 50 to 70 percent to
anthropogenic influences, including direct warming by greenhouse gases, and the
second-order influence of atmospheric circulation patterns.

Overall, Arctic sea ice has declined by 12,000 cubic
kilometers since 1980.As noted in the
section about Antarctica, there is no sea level impact due to the melting of
floating ice, but there is an impact on the earth’s heat budget.

The loss of sea ice in some of the peripheral seas of the Arctic Ocean (Chukchi Sea, Bering Sea, Barents Sea, and others) is more evident.

Image Credit, Rick Thoman, National Weather Service, Fairbanks

Continental Glaciers

Continental glaciers are melting.

People who live near glaciers are well aware of the
historical and current melting of glaciers.In Alaska and Western Canada, popular glaciers often have signposts or
old photographs showing the earlier extent of the glaciers.Some examples are the Columbia Ice Field in
Alberta between Banff and Jasper National Parks, and in Alaska, Root Glacier
near Kennecott mine, Exit Glacier near Seward, Portage Glacier and associated
glaciers near Anchorage, and the many tidewater glaciers along the Alaskan
coast, including Glacier Bay near Juneau, College Fjord near Valdez, the
glaciers of Kenai Fjords National Park, and Columbia Glacier near Valdez.Glaciers are in retreat, on a scale which is
noticeable from year to year and dramatic over the course of decades.

The UN Glacier Monitoring Service and its predecessor
organizations have measured the melting of continental glaciers, other than
Greenland & Antarctica.WGMS issued
major reports in 2008 and 2015; each report shows overwhelming evidence of melting
of glaciers worldwide.WGMS includes
data on about 100,000 glaciers, with digital outlines of about 62,000 glaciers;
data on glacier fluctuation includes over 35,000 length observations for nearly
2000 glaciers (as of 2008).Detailed
mass balance observations are conducted on a smaller number of reference
glaciers (including the most volumetrically significant glaciers).Data from reference glaciers are extrapolated
to other glaciers on the basis of regional association, altitude and latitude.

At any given time, a small number of glaciers are growing,
due to natural fluctuations of snowfall, warmth, and air circulation. But the
great majority of glaciers worldwide are melting.

Annoyingly, the WGMS does not report summary ice loss in
terms of cubic kilometers or gigatonnes.Glacial Mass Balance is reported in terms of meters of water equivalent,
a vertical measure of average ice melted.Volumes of melted ice can be calculated from the reported total area of
glaciers under study.Those volumes can
then be used for purposes of understanding the global heat budget and sea level
rise.

Sea Level

The earth entered a period of cyclic ice ages about 3
million years ago. The last 600,000
years have been characterized by ice age cycles of about 100,000 years,
apparently triggered by variations in earth’s orbit. The influence of the orbital cycles is
enhanced by feedback mechanisms, including CO2 and the reflectivity of
ice. The peak of the last glacial cycle
occurred only about 20,000 years ago, and remnants of ice may have persisted in Ontario until about 8,000 years ago.

Deglaciation following the last ice age was mostly complete
by 8000 years ago.We know this from
studies of sea level and sediment cores.Sea level rose by about 80 meters between 14,000 years ago and 8000
years ago, an average rate of 1.3 cm/year.From 7500 years ago to the 20th century, sea level rose only
5 meters, a rate of 0.07 cm/year.Through the 20th century, sea level
rose at about 0.2 cm/year, a significant increase over the background rate.Satellite data over the past 25 years shows
that sea level rise has accelerated to 0.35 cm/year, five times the rate of sea level rise for the past 7500 years. This is a clear indication that global
warming from human greenhouse gases is contributing to melting ice.

Additional heat retained by greenhouse gases will result in
a faster rate of melting ice, and higher sea level rise. Current forecasts of sea level rise range
from about 2 feet to 8 feet by the end of the century. Sea level rise of only 4 to 6 feet would seriously damage some coastal communities around the world, including the inundation of barrier island and low-island communities.

Heat Budget

From 2003 to 2016,
greenhouse gases retained 1.6 x 1023 joules
of heat in the atmosphere, according to tables of radiative forcing published
by NOAA (https://esrl.noaa.gov/gmd/aggi/aggi.html). This figure for anthropogenic heat does not
include the effect of cooling or warming aerosols, primary heat from fossil
fuels and deforestation, or other minor sources of heat. Estimates for some of these other anthropogenic
disturbances are found in the IPCC 5 report, but only through the year 2011.

We have good estimates of the cumulative ice lost from
Antarctica, Greenland, Arctic sea-ice and Continental Glaciers from 2003 to
2016, due to high-quality satellite observations. About 10,400 gigatonnes of ice was lost over
that period. The heat required to warm (+10 C) and melt that volume of ice is 3.7 x
1021 joules, or about 2.3% of the total
heat retained by greenhouse gases.
The allocation of heat to warm the ice by 10 degrees C was to reflect
heating of an equivalent amount of ice, which has not yet melted. Average temperatures of -10 C from core-holes
in Greenland and Antarctica were taken as the ambient temperature of ice before
melting.

Considering that about 2.9% of the earth’s surface is covered by ice, this seems like a reasonable distribution of greenhouse heat which is going to warm and melt ice. Looking forward, if a higher percentage of heat goes towards melting ice, sea level will necessarily rise faster. Possible reasons for faster melting of ice could be more rapid ice flow from Antarctica and Greenland. This might occur as the base of the ice is lubricated by meltwater, or when restraining ice shelves are lost around Antarctica.

Saturday, April 21, 2018

The world’s oceans are warming. Ocean warming is the strongest confirmation
that greenhouse gases are warming the planet.

The heat capacity of water is among the highest of common
substances.That means that water can absorb
a large amount of heat while its temperature changes only slightly.The measurable warming of the world’s oceans
indicates that a very large amount of heat has come from somewhere.The only credible source for so much heat is
the retention of heat by atmospheric greenhouse gases.Let’s look at the source of the data, and the
numbers.

ARGO Oceanographic Program

Rising ocean temperatures have been measured by
oceanographic surveys since the 1970s.However,
these ocean surveys were limited in geographic coverage and continuity of data
acquisition.A more comprehensive
system, ARGO, was put in place beginning in the early 2000s, with improvements
and new deployments continuing today.Today, ARGO consists of nearly 4000 floats which continuously measure
ocean temperature, salinity, density and currents from the surface to 2000
meters.

ARGO floats measure temperature to an accuracy of
two-thousands (0.002) of a degree Celsius.The floats are “parked” at 1000 meters, and every ten days submerge to
2000 meters and return to the surface, where data is broadcast to satellite
receivers.The system provides
comprehensive coverage worldwide except for polar latitudes, and continuous
measurements.

Ocean *Weather*

Like the atmosphere, ocean temperatures are seasonal,
cyclic, variable, and turbulent.The
large number of ARGO floats was designed to adequately measure and characterize
the variable temperatures of the ocean.The
volume of data acquired allow scientists to make maps of the changing water
temperature and calculate the total heat content in the ocean.

Observations

Surface temperatures are warming the fastest.NOAA presents charts of average ocean
temperature and ocean heat content according to water depth, based on ARGO
observations and earlier oceanographic studies.

Surface waters (0 – 100 m) have warmed by about 0.6 degrees
C on average since the late 1960s.

Intermediate waters (0 – 700 m) have warmed by a little over
0.2 degrees C on average since the late 1960s.

Relatively deep waters (0 – 2000 m) have warmed by about 0.1
degree C on average, since the late 1960s.

Over all depth increments observed, the rate of warming
seems to be slightly increasing.

Heat Content

The changing heat content of the ocean is a simple function
of the change in temperature.The heat
capacity (or specific heat) of water represents the amount of heat required to
change the temperature of a given volume of water.From an observed change in temperature, we
can back-calculate the amount of heat that has entered the ocean.The density and heat capacity of water change slightly with
pressure (and water depth). NOAA has calculated
the heat content of the ocean over various depth intervals from the temperature data and heat capacity.

The heat content of the ocean at intermediate depths (0 –
700 m) has increased by about 2 x 1023 joules since the late
1960s.

The heat content from the surface to 2000 meters (0 – 2000 m) has
increased by about 3 x 1023 joules since the late 1960s.This means that the heat content over the
interval from 700 m to 2000 m has increased by about 1 x 1023
joules, about half of the increase in heat content at intermediate water
depths.

Source of Increasing Heat

NOAA unfortunately did not report temperature change or heat
content in separate depth intervals, but only in overlapping intervals of 0 –
100 , 0 – 700, and 0 – 2000 meters.Starting from the average change of temperature for each interval, I
calculated the heat content for 0 – 100 m, 100 – 700 m, and 700 – 2000 m.My figure for total heat content calculated
from temperature change exceeds the heat content reported by NOAA by 14%,
probably due to errors in my single-point values for temperature or heat
capacity over these depth intervals.

Temp
Rise (C)

Volume
(km3)

Density
(g/cc)

Mass
(kg)

Heat
Capacity (J/kg-C)

Change
in Heat Content (J)

0 -
100 m

0.6

5.23E+07

1.025

5.10E+19

3928.00

1.20E+23

0 -
700 m

0.2

3.69E+08

1.034

3.57E+20

3421.50

2.44E+23

0 -
2000 m

0.1

1.36E+09

1.329

1.02E+21

3339.04

3.41E+23

Intervals

Change
in Heat Content

Percent
of Heat Change

Change
in Heat Content per 100 m

0 -
100 m

1.2E+23

35%

1.2E+23

100 m
- 700 m

1.2E+23

36%

2.1E+22

700 m
- 2000 m

9.6E+22

28%

7.4E+21

There is a large difference between the heat gained in the
upper 100 meters of the ocean and the heat gained at deeper levels by
equivalent volume.The ocean is clearly
heating from the surface downward.About
35% of the total heat increase has occurred in the upper 100 meters of the
ocean, about 36% in the next 600 meters, and about 28% in the next 1300
meters.Research on deep ocean currents shows
that heat is also being introduced into the deep ocean by currents, rather than
by conduction.

The geographic distribution of ocean heating also shows
atmospheric influence.The ARGO ocean
data shows distinct heating anomalies between 30 and 40 degrees of latitude,
north and south.These are the
down-welling points of large atmospheric convection cells termed Hadley cells.You can see atmospheric circulation in
observations of ocean warming.

Conclusion

The first post in this series quantified anthropogenic heating
and cooling, primarily from greenhouse gases, particularly CO2.This post looked at the largest heat sink on
earth – the oceans.

Net Anthropogenic heat absorbed by the planet from 1970 to 2016 was about 3.4 x 1023
joules. Over the same period, the heat
content of the oceans has increased by about 3.0 x 1023 joules. Anthropogenic heat is the only credible source for the heat appearing in the ocean, and the warming oceans confirm that greenhouse gases are, in fact, warming the planet.

Wednesday, April 11, 2018

I have been away from my blogs for far too long.I will try to post a series on the global
heat budget.

Previously, I posted a lot of work on atmospheric
CO2, considering the geographic distribution, isotope data, rates of change,
comparison to man-made emissions from various sources, and interaction of the
atmosphere with global carbon reservoirs.The latest summary post is here:

I deliberately avoided the question of climate change to focus
on the science of atmospheric CO2.

For the past year, I’ve been studying on the problem of
global warming (the first-order consequence of greenhouse gases) and climate
change (the higher-order consequences of greenhouse gases).And I’ve been posting less while I worked to understand the data.

I’m going to present what I’ve learned as a series of
short posts, rather than writing a book.

The very short version is this:

The Global Heat Budget; The Very
Short Version

People have raised the concentration of
atmospheric CO2 by burning fossil fuels.
The volume of CO2 released by fossil fuels has increased sharply since about 1950, and continues to increase today.

CO2 and other greenhouse gases
retain heat in the atmosphere. The
quantity of heat is easily calculated as a function of the concentration of CO2
in the air. We can calculate the amount
of heat that has been trapped to date, and we can forecast the heat that will
be trapped in the future.

Heat is increasing in heat sinks on
earth. Observations show that the amount
of heat appearing in earth’s heat sinks is approximately equal to the heat
retained by greenhouse gases. The heat
is showing up as rising ocean temperatures, melting ice, and a warmer
atmosphere. The quantity of heat
appearing in these systems has been measured by high-accuracy monitoring programs
since about 2003. The warming ocean
accounts for about 95 percent of our estimates of anthropogenic heat. Retained heat due to greenhouse gases is the
only credible source for the heat appearing in heat sinks.

Sea-level is rising. Sea level rise has been documented by tidal gauges
for 130 years, and by high-accuracy satellite measurements since 1992. The amount of sea level rise matches the
observed volumes of melted ice, thermal expansion of the ocean, and
ground-water extraction. The fact of rising sea
level confirms observations of melting ice and warming oceans.

Higher atmospheric CO2
concentrations are inevitable for the foreseeable future. Quantitative forecasts of future heating
indicate serious and expensive problems will develop for the nation & the
world.

The physics of CO2 as a greenhouse gas is settled science,
based on published studies dating back over 150 years.High accuracy programs to measure melting
ice, ocean temperatures, and rising sea level have been in place in recent
decades, long enough to yield conclusive results.

Carbon dioxide was first proved to be a greenhouse gas by
John Tyndall in 1859, proving
speculation that began in 1820.The
planet-wide effect of changing CO2 concentrations was calculated by the Swedish
chemist Arrhenius and published in 1896.Arrhenius was originally attempting to find
the cause of the ice ages, but later recognized the possibility that fossil
fuel emissions could change the climate, and published that result in 1906.Quantitative measurements of CO2 and rising temperatures were published
in 1938 by Guy Callendar.Systematic global measurements of CO2
concentrations began in 1955 by
Charles Keeling.Satellite measurements
of sea level rise began in 1992.Satellite measurements of Antarctic and
Greenland ice mass began in 2003.Detailed, comprehensive and continuous
measurements of ocean temperatures began in 2004.

Calculation of Heat Retained
by Greenhouse Gases

Greenhouse gases are mostly transparent to wavelengths of
visible light, which carry most of the energy from our sun.Visible light strikes the earth and is converted
to heat.Normally, some portion of that
energy is re-radiated into space as thermal infrared radiation.But greenhouse gases are opaque to infrared
wavelengths, and trap heat in the atmosphere as a function of the concentration
of those gases.As greenhouse gases have
accumulated in the atmosphere, lower levels of the atmosphere have warmed.Higher levels of the atmosphere have cooled,
as more heat has been trapped near the surface.

NOAA publishes historical tables of the atmospheric heating
coefficients (known by the awkward and uninformative phrase *radiative
forcing*) for anthropogenic greenhouse gases, dating back to 1979.The coefficients are prepared according to
international standards, taking into account cloudiness and angle of solar
incidence to yield a global average.You
can do the math yourself to calculate annual heat retained by each greenhouse
gas, which I have done. Carbon
dioxide represents about two-thirds of the heat retained in the atmosphere by
greenhouse gases.Methane, nitrogen
oxide, chlorofluorocarbons (CFCs) and minor greenhouse gases account for the
rest of the heat retained by greenhouse gases.

In 1979, greenhouse gases retained about 7 x 1021
joules.By 2016, greenhouse gases
retained about 1.2 x 1022 joules, an increase of 78% in annual
heating.It’s difficult to conceptualize
how much heat is represented by 1022 joules.A joule is about ¼ of a standard calorie –
the heat required to raise a gram of water by one degree C.It’s a small amount of heat.But 12,000,000,000,000,000,000,000 joules is
a lot of heat.Later in this series, we’ll
consider how the earth can absorb that quantity of heat, and where the heat is
going.

Aerosols and Anthropogenic
Cooling

Aerosols are the least-well quantified anthropogenic
influence on earth’s climate.Sulfate
aerosols cool the atmosphere by making clouds more abundant and
reflective.Sulfates can originate from
volcanic eruptions, but are also a common industrial pollutant.Carbon black aerosols warm the atmosphere by
absorbing sunlight.

Sulfate emissions have dropped dramatically in the United
States and Europe over the past 25 years, thanks to regulations intended to
limit acid rain, but world-wide sulfate emissions have continued to grow.The average global impact of sulfates and
black carbon aerosols is shown in the following graphs, but the more significant impacts are
regional.South Asia suffers from the
greatest carbon black emissions and impact, while China is now the source of
most sulfate emissions.

IPCC Net Anthropogenic
Heating and Cooling

The IPCC (International Panel on Climate Change) 5th Climate
Assessment contains a table of anthropogenic heating and cooling
coefficients.The IPCC numbers for
conventional greenhouse gases are identical to NOAA, but IPCC also recognizes
other anthropogenic factors, which can both heat and cool the atmosphere.These factors act by direct absorption of
sunlight, or by a greenhouse effect that is restricted to certain levels in the
atmosphere.The IPCC recognizes the
warming factors of tropospheric ozone (O3), stratospheric water vapor (H2O),
black carbon on snow, and contrails.IPCC recognizes cooling factors, including land-use changes (which
affect the reflectivity of the earth), stratospheric ozone, and aerosols.

Here is a chart based on IPCC data, showing anthropogenic heating and cooling coefficients (*radiative forcing*).

Primary Anthropogenic and Other
Heat

Strangely, to me, the IPCC report makes no mention of another
source of anthropogenic heat – the primary heat resulting from burning fossil
fuels and nuclear plants, and secondarily, the primary heat resulting from
deforestation.The global heat from
non-renewable sources is reported in the BP Statistical Review of World Energy.The energy released by deforestation can be
easily calculated from the volumes of carbon dioxide released, which is
estimated in several sources.These
sources of heat represent about 5% and 1%, respectively, of the net
anthropogenic heat reported by IPCC, and exceed several other minor sources of heat in
the report.

Here is a chart showing the calculated anthropogenic heating and cooling, based on IPCC estimates for radiative forcing, plus heat from primary energy.

I considered and calculated the incremental accumulation of
geothermal heat, due to the retention of heat by greenhouse gases. Geothermal heat is normally in a steady
state, with heat flux from the planet balanced by thermal radiation into
space. The quantity of heat retained is
quite small, however, and not worth adding to the heat budget.

Agriculture has a significant influence on the planet’s
seasonal CO2 cycles, due to the preponderance of agriculture in the temperate
Northern Hemisphere.Changes in
atmospheric CO2 necessarily imply changes in heat, through the reduction and
oxidation of carbon.Agriculture appears
to be a zero-sum influence on the long-term heat budget but may be significant
in seasonal climate modeling.

Net Anthropogenic
Heat

The net heating coefficient (*radiative forcing*) for all anthropogenic heating and cooling was about 2.4 watts/m2 in 2011. The global average for solar insolation at the top of the atmosphere is 1361 watts/m2. About 1000 watts/m2 of the sun's radiation reaches the earth's surface. Anthropogenic heat represents a small but noticeable increment to the natural heating of the earth by the sun, about 0.24% above the natural, steady state of solar heating and radiative cooling.

Using the IPCC heating and cooling numbers, plus primary heat,
we see that net global anthropogenic heating was 9.8 x 1021 joules in 2011.

That’s enough heat to melt about 29,500 gigatonnes of ice, or to bring 14,000 gigatonnes of water from room temperature to boiling.Of course, the icecaps are much larger than 29,500 gigatonnes of ice, and the ocean is much larger than 14,000 gigatonnes of water.So the changes we see in a single year are subtle.

Net anthropogenic heat from 1970 to 2016 is about 3.4 x 1023 joules. The effect of heat retained by greenhouse gases is cumulative. Over time, the consequences are not so subtle. In the next few posts, we will look at how
anthropogenic heat is being distributed in earth’s heat sinks.

Aerosols caused by human activity play a profound and
complex role in the climate system through radiative effects in the atmosphere
and on snow and ice surfaces and through effects on cloud formation and
properties. The combined forcing of aerosol–radiation and aerosol–cloud
interactions is negative (cooling) over the industrial era, offsetting a
substantial part of greenhouse gas forcing, which is currently the predominant
human contribution. The magnitude of
this offset, globally averaged, has declined in recent decades, despite
increasing trends in aerosol emissions or abundances in some regions. (emphasis mine).

By nucleating a larger number of smaller cloud drops,
aerosols affect cloud radiative forcing in various ways. (A) Buffering in
nonprecipitating clouds. The smaller drops evaporate faster and cause more
mixing of ambient air into the cloud top, which further enhances evaporation.
(B) Strong cooling. Pristine cloud cover breaks up by losing water to rain that
further cleanses the air in a positive feedback loop. Aerosols suppressing
precipitation prevent the breakup. (C) Larger and longer-lasting cirrus clouds.
By delaying precipitation, aerosols can invigorate deep convective clouds and
cause colder cloud tops that emit less thermal radiation. The smaller ice
particles induced by the pollution aerosols precipitate more slowly from the
anvils. This can cause larger and longer-lasting cirrus clouds, with opposite
effects in the thermal and solar radiation. The net effect depends on the
relative magnitudes.

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This blog is about economics, energy, public policy, science, and other things too important to ignore and too dreary for Facebook.

About me, consider my favorite quote about Don Quixote, from "The Man of La Mancha":

...A country gentleman, no longer young. Being retired, he has much time for books. He studies them from morn to night, and often through the night and morn again, and all he reads oppresses him; fills him with indignation at man's murderous ways toward man. He ponders the problem of how to make better a world where evil brings profit and virtue none at all; where fraud and deceit are mingled with truth and sincerity. He broods and broods and broods and broods, and finally his brains dry up. He lays down the melancholy burden of sanity...."